Officials say ten lifeguards at a public pool in Manhattan were taken to a hospital for chlorine exposure.

Manhattan Parks and Recreation spokeswoman Melissa Kirkwood says the lifeguards were exposed Wednesday at Northview Pool. KSNT-TV reports that patrons weren’t sickened because the chlorine apparently was released during a break that gives the lifeguards a chance to get into the pool and cool down while everyone else gets out of the water.

Kirkwood blamed the release on an equipment malfunction that was caused by a lightning strike earlier this month. The Manhattan Fire Department was able to contain the leak late Wednesday afternoon, but the pool remains closed for now.